Congenital heart disease

Question 1

What is a congenital heart defect?

Answer 1

It is a general term used to describe abnormalities of the heart or great vessels present from birth

• Faulty embryogenesis (week 3-8)
• Usually monomorphic (single lesion) like ASD, VSD,
• Might not be evident until adult life (like coarctation or ASD)
• its incidence in the USA is 1%
• Noninvasive methods like Ultrasound, MRI, and CT increases the early detection

Question 2

Describe the pathogenesis of congenital heart defects

Answer 2

• Faulty embryogenesis during the gestational weeks of 3-8, when the major CVS structures develop
• Unknown in 90% of the cases
• In 10% well defined genetic or environmental influences are identifiable

Question 3

What are the genetic causes of congenital heart disease?

Answer 3

• Trisomies 21 (down syndrome) along with genes 13, 15, 18, and XO
• Mutation of genes that encode for the transcription factors TBX5 & NKX2.5 results in ASD
• VSD is observed in Holt-Oram syndrome, a rare hereditary condition associated with heart, arm, and hand defects
• Mutation 22q11.2 deletion of chromosome 22, an important chromosome in heart development (conotruncus, brachial arch, and face) observed in 15-50% of the disorders

Question 4

What are the environmental causes of congenital heart defects?

Answer 4

1) Congenital rubella infection

2) Gestational diabetes

3) Exposure to teratogens (Including some therapeutic drugs) responsible for additional cases

Question 5

What are the clinical features if congenital heart abnormalities?

Answer 5

• A shunt is an abnormal communication between chambers or BV

1) Left to Right chamber shunt

• Cyanosis can occur due to deoxygenated blood shunting (Eisenmenger syndrome)
• If significant pulmonary hypertension is irreversible
• Septic emboli that arises in the peripheral veins can bypass normal filtration action of the lungs, causing brain infarction and abscess

2) Obstructions

• Coarctation of Aorta
• Pulmonary stenosis/atresia
• Aortic stenosis/atresia

Question 6

What are the most commonly encountered left-to-right shunts?

Answer 6

1) Atrial septal defect

2) Ventricular Septal Defect

3) Patent Ductus Arteriosus

4) AV septal defect

Question 7

What is atrial septal defect?

Answer 7

• ASD results in an L-R shunt, as the pulmonary resistance is less than the systemic vascular resistance in addition to the fact that the compliance of the right ventricle is greater than the LV
• ASD is mainly not symptomatic before 30 years old
• A murmur is heard due to the excessive flow through the pulmonary valve
• Eventually volume hypertension of the RA & RV develops

Question 8

What is ventricular septal defect?

Answer 8

• Incomplete closure of the ventricular septum forming a shunt between LV & RV
• It is the most common CHD
• In 90% of the cases the membranous septum is involved
• In the other 10% when the muscular septum is involved, multiple holes (swiss-cheese-septum) are found

Question 9

What is the clinical presentation of septal defects?

Answer 9

1) The small ones close spontaneously

2) The large ones with a significant L-R flow will develop RV hypertrophy, and pulmonary hypertension leading to an irreversible pulmonary vascular disease in all patients with large unoperated VSD which will lead to cyanosis and death

Question 10

What is meant by patent ductus arteriosus?

Answer 10

• When the ductus arteriosus remains open after birth
• It does not produce functional difficulties at birth but a harsh machinery murmur
• an obstructive pulmonary vascular disease might lead to Right to Left shunt as hypertension approaches the systemic pressure

Question 11

What are the malformations that cause right-to-left shunts?

Answer 11

• All have “T” in their names:

1) Tetralogy of fallout

2) Transposition of great arteries

3) Truncus arteriosus

4) Total anomalous pulmonary venous connection

5) Tricuspid atresia

Question 12

What is meant by the tetralogy of Fallot?

Answer 12

• The most common form of cyanotic CHD
• Results from the anterior superior displacement of the infundibular septum

1) Large VSD

2) Obstruction to the RV flow (subpulmonary stenosis)

3) Aorta overrides the VSD

4) right ventricular hypertrophy

• These four findings are a must
• Even if untreated the patient will most likely to survive to adulthood, in X-ray it has a boot-shaped sign due to the marked right ventricular hypertrophy

Question 13

What are the clinical presentations of tetralogy of fallout?

Answer 13

• The severity of the obstruction determines the direction of blood flow, which depends on the pulmonary outflow obstruction

1) No cyanosis if the subpulmonary stenosis is mild, L-R-Shunt

2) In more severe subpulmonary stenosis, R-L-SHUNT and cyanosis will occur

3) With increasing severity of stenosis, the pulmonary artery gets progressively smaller and thinner and the wall gets hypoplastic, the aorta will progressively get larger

• The child grows and the heart increases in size while the pulmonary orifice does not, the obstruction will progressively worsen, and thus most infants are cyanotic from birth
• Complete surgical repair is possible if it is not complicated

Question 14

What is meant by the transposition of the great arteries (TGA)?

Answer 14

• When the aorta arises from the right ventricle and the pulmonary artery emanates from the left ventricle
• A shunt is needed for survival
• RV thickness is greater than the LV
• Deoxygenated blood from the body (right side) is pumped right back out (aorta). Oxygenated blood coming from the lungs (left side) is being pumped right back to the lungs (pulmonary trunk)
  In this case, a shunt is essential for survival. The actual management would be to cut and switch the locations of the arteries.
• While waiting for surgery, a medicine called prostaglandin may be used to keep the ductus arteriosus open and allow for better mixing of oxygenated and deoxygenated blood

Question 15

What is meant by truncus arteriosus?

Answer 15

• It is a developmental failure of separation of the embryologic truncus arteriosus into the aortic and pulmonary artery, where a single great artery receives blood from both ventricles
• It is accompanied by an underlying VSD, which gives rise to the systemic, pulmonary, and coronary circulations

Question 16

What are the examples of obstructive congenital heart disease?

Answer 16

1) Coarctation of aorta

2) Pulmonary stenosis/atresia

3) Aortic stenosis/atresia

Question 17

What is meant by the coarctation of the aorta?

Answer 17

• The narrowing/constriction of the aorta, the most important form of obstructive congenital heart disease
• Occurs in males twice more, although females with Turner syndrome commonly have aortic coarctation
• In 50% of cases it is accompanied by a bicuspid aortic valve

Question 18

What are the different types of the coarctation of the aorta?

Answer 18

1) With PDA

• In infants
• Narrowing plus a shunt between the arteries: blood goes from the pulmonary artery to the descending aorta (due to the obstruction, the BF to the descending aorta is minimized so the pressure in the pulmonary trunk becomes higher than the descending aorta hence the R – L movement) – cyanosis in the lower half and usually presents very early, complicated by the tubular narrowing of the aortic segment

2) Without PDA

• In adults
• Ridgelike unfolding of the aorta distal to the ligamentum arteriosum
• The upper limb will have high pressure while the lower limb will have a low pressure

Question 19

What are the clinical presentations of coarctation of the aorta with a PDA?

Answer 19

• Depends on the severity of the narrowing and the patency of the ductus arteriosus:

1) Many infants can’t survive the neonatal period without a surgical or catheter-based intervention, delivering unsaturated blood through the ductus arteriosus produces cyanosis localized to the lower half of the body

Question 20

What are the complications of the coarctation of the aorta without PDA?

Answer 20

• Mostly asymptomatic which might go unrecognized until adult life
• HTN in upper extremities with low pulse and low pressure in the lower extremities
• Collateral develops to compensate for the low pressure in the lower ectrimity
• Thrill/systolic murmur
• Due to the LV hypertrophy there might be cardiomegaly
• surgical resection and end-to-end anastomosis or replacement by a prosthetic graft yields excellent results

Question 21

What are the most frequent congenital cardiac malformations?

Answer 21

1) VSD (4482/1 MILLION)

2) ASD (1043/1 MILLION)

3) Pulmonary stenosis (836/1 million)

Question 22

What is heart failure?

Answer 22

A pathologic state where there is an impairment of cardiac function, and thus the heart is unable to maintain sufficient output to meet the metabolic requirements

• It is a common endpoint of many heart disease
• Congested heart failure is complicated by diminished CO (forward flow), and accumulation of blood in the venous system (backward flow)

Question 23

What is the mechanism by which heart failure can occur?

Answer 23

1) Systolic dysfunction (Abnormal pumping)

• Progressive deterioration of the myocardial contractile function, due to ischemic injury, pressure or volume overload, dilated cardiomyopathy

2) Diastolic dysfunction (a problem in heart filling and relaxation)

• Inability of the heart chambers to relax during diastole, due to left ventricular hypertrophy, amyloidosis (accumulation of amyloid “abnormal protein deposition”), constrictive pericarditis

Question 24

What are the mechanism that the CVS do to compensate for the reduced myocardial contractility, or increased hemodynaic burden?

Answer 24

1) Tachycardia

2) Ventricular dilation (improves contraction due to the myofibril stretching)

3) Salt and water expansion increasing the blood volume

Question 25

Describe the morphology of heart failure

Answer 25

• Varies depending on the cause of the disease process, abnormalities like MI or valvular deformity, in hypertension the chambers are hypertrophies while in ischemia there is necrosis

Question 26

What are the pulmonary changes that are associated with HF?

Answer 26

pressure in the pulmonary veins is transmitted to the capillaries and arteries resulting in pulmonary congestion, and edema, with heavy wet lungs

• The patient complains of inability to sleep lying down without a pillow

It will also include:

1) Perivascular and interstitial transudate, mainly in the intralobular septa which shows Kerley’s B lines on the X-ray

2) Progressive edematous widening of the alveolar septa

3) Accumulation of hemosiderin-containing macrophages in the alveoli (siderophages/HF cells), all BVs are engorged with RBCS which might cause BV to rupture and release RBCs. They can then get destroyed and release hemosiderin which will get engulfed by macrophages – heart failure cells (gold-brown appearance)

Question 27

What are the clinical manifestations of heart failure?

Answer 27

1) Dyspnea (breathlessness)

2) Orthopnea (dyspnea while lying down, relieved by standing or sitting)

3) Coung (common in left side heart failure)

• Due to fluid limiting gas exchange

Question 28

What is the reaction of the kidneys to HF?

Answer 28

Due to decreased CO, their will be a decrease in renal perfusion which will result in the activation of the renin-angiotensin-aldosterone mechanism, if the reduction in renal perfusion is severe this could result in azotemia (reduced clearance of waste by the kidneys accumulating in the body)

Question 29

What is meant by cor pulmonale?

Answer 29

It is when a HF occur due to lung disease, like chronic obstructive airway disease

Question 30

What happens to thw liver in Risght side heart failure?

Answer 30

1) Increased in size and weight (hepatomegaly)

2) Prominent congestion

3) Congested red centers of the liver lobules are surrounded by paler, and sometimes fatty peripheral regions (nutmeg liver)

• Right side HF leads to elevated pressure in the portal vein and its tributaries, producing a tensed enlarged spleen (congestive splenomegaly)

Question 31

What are the morphologic and clinical effects of pure Right side heart failure?

Answer 31

• The main presentation is the accumulation of fluid in the periphery, engorging the systemic and portal venous system
• In most cases, it is a secondary consequence of left-side HF

Question 32

What happens to the subcutaneous tissue in right side heart failure?

Answer 32

1) Peripheral edema of some portions, especially the ankle, is a hallmark of right-side heart failure, in bedridden patients the edema might be presacral

2) Generalized massive edema is called anasarca

• Apply pressure on the edema in the ankle if it remains inward for a while it means that it is a pitting edema and it might indicate right-side heart failure